Supportability

There is an expanded set of capabilities that are also necessary when addressing non-functional requirements – those that are very relevant specially when your reusable component or service grows in popularity and usage. They fall under two categories: operational agility and fault-tolerance. Here are a few candidate capabilities in both these categories:

Operational Agility / Supportability:

• Ability to enable / disable both services and operations within a service

• Ability to provision additional service instances based on demand (elastic scaling)

• Maintenance APIs for managing resources (reset connection pool, individual connections, clear cached data, etc.)

• Ability to view Service APIs that are breaching and ones that are the risk of breaching operational SLAs

• Model and detect out of band behavior with respect to resource consumption, transaction volumes, usage trends during a time period etc.

Fault Tolerance:

• Failing fast when there is no point executing operations partially

• Ability to detect denial of service attacks from malicious clients

• Ability to gracefully handle unexpected usage spikes via load shedding, re-balancing, deferring non-critical tasks, etc.

• Detecting failures that impact individual operations as well as services as a whole

• Dealing with unavailable downstream dependencies

• Leveraging time outs when integrating with one or more dependencies

• Automatically recovering from component failures

It is also important to point out that both these aspects are heavily interconnected and influence each other.